Broach checker



W. S. PRAEG Aug. 20, 1957 Filed Aug. 15, 1955 United States Patent 2,803,066 BROACH CHECKER Walter S. Praeg, Detroit, Mich., assignor to National The present invention relates to a broach checker, and more particularly, apparatus for checking both lead and involute. of relatively massive broaches.

The increased acceptance by industry of broaching has led to the adoption of extremely large broaches intended to perform operations involving a high degree of accuracy. In order that the accuracy expected of these broaches shall be maintained, it is of course essential that accurate apparatus be provided for checking the broaches.

It is accordingly an object of the present invention to provide highly efficient easily operated apparatus for checking lead and involute characteristics of relatively large broaches.

It is a further object of the present invention to provide broach checking apparatus comprising a base having a column designed to afford temporary support for a rela tively massive broach to facilitate mounting and de-. mounting the broach from the apparatus.

It is a further object of the present invention to provide combined lead and involute checking apparatus for a broach including means for supporting a broach, a lead bar coupled to the broach in axial alignment therewith, a slide movable axially of the broach and lead bar, a nut on the slide adapted to impart predetermined rotation to the lead bar and broach, and an indicator carried by the slide adapted to afford a comparison of the lead on the broach with respect to the master lead provided on the lead bar.

It is a further object of the present invention to provide lead checking apparatus as described in the preceding paragraph comprising means for coupling the lead bar and broach including means for interrupting the driving relation between the lead bar and broach to permit the means to constitute a bearing for rotation of the broach independent of the lead bar, a base roll operatively to constitute a bearing for a lead bar 22. At its lower end the member includes a socket portion 24 adapted to receive the upper cylindrical end portion 26 of a broach to be checked. Suitable clamping means, such for example as set screws, one of which is indicated at 28, may be provided for selectively clamping the broach to the socket 24 for rotation therewith.

The broach proper is indicated at B and at its lower end it is supported by a driving center 30 adapted to be raised and lowered in parallelism with the inclined front face of the column 12 by a hand wheel indicated at 32. Suitable releasable or removable drive means such as dog 31 clamped to the broach and forming a driving connection between the center 30 and the lower end of the broach B are provided, so that rotation may be imparted to the broach B by rotation of the driving center 30 for one operation, and rotation of the broach connected in axial alignment with the broach, and cross slide means operatively connected to the base roll and including an indicator having a movable finger selectively engageable with flanks of teeth on the broach for etfecting an involute check by transverse movement of the slide accompanied by corresponding rotation of the broach.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawing, wherein:

Figure l is a perpective view of the combined lead and involute checker for a broach.

Figure 2 is an enlarged perspective view showing means for driving the center and means for coupling the center to the broach.

The broach checker comprises a base 10 having a vertically extending column 12 at the rear thereof, the front face of the column being upwardly and rearwardly inclined at a small angle as illustrated. Fixedly secured to the front face of the column 10 at the top thereof is an upper or outboard bracket 14 which may be vertically adjusted to accommodate different size broaches andlead bars as will later appear. For this purpose the front face of the column is provided with vertically extending T- slots 16. Also vertically adjustable in the T-slots 16 is an intermediate bearing 18 having rotatably secured therein a member 20 adapted to be fixedly secured to and B may be provided by rotation of the lead bar 22 for another operation. 7

The inclined front face of the column 12 is provided with generally vertically extending ways 34 in which is mounted a slide 36. At its upper end the slide 36 has secured thereto a lead nut 38 which will be provided with take-up or anti-backlash means. As a result, up and down movement of the slide 36 in the ways 34 will result in corresponding rotation of the lead bar 22 and hence of the broach B when the set screws 28 are tightened. Also carried on'the slide 36 is a block 40 having horizontally extending ways 42 in which is slidable an indicator mounting 44 carrying an indicator, the dial of which is indicated at 46. The indicator includes a movable finger 48 adapted to engage the side of a tooth of the broach B.

To insure proper registration between the broach and the movable finger 48 when the broach is initially placed upon the checking apparatus, an appropriate locator de vice 49 is provided having a retractable finger 50 movable as a result of operation of a lever 52 into a tooth space of the broach so as to position the same in proper angular relation for coaction with the movable finger 48 of the indicator. The finger 50 is of course retracted before a lead comparison is made.

In order to counterbalance the weight of the slide 36, a pulley 54 is provided at the top of the column and a cable 56 connected at one end to the slide and at the other end to a counterweight 58 is led over the pulley 54.

Movement of the slide 36 generally vertically and longitudinally of the ways 34 may be accomplished manually by suitable conventional mechanism including a hand wheel indicated at 60. If preferred, automatic vertical movement of the slide 36 may be accomplished by suitable motor means housed within the frame and column and for this purpose push buttons indicated at 62 are provided. A selector clutch is provided for connecting the slide feed mechanism to the hand wheel 60 or the motor means, this clutch means including an operating handle indicated at 64.

Located on the base of the frame in ways indicated at 66 is a carriage 68 adjustable in the ways by manually operated means including the hand wheel '70. The carriage 68 in turn is provided with transverse guide structure cooperating with ways 72 formed at the underside of a cross slide 74 which carries an indicator 76 operably connected to a movable finger 78 engageable with the side of a tooth on the broach B. Associated with the driving center 30 is a base roll 79 operatively connected as by tapes, friction means, or otherwise, to the cross slide 74 so that rotation is imparted to the base roll 79 in accordance with transverse movement of the cross slide 74.

In Figure 2 tapes 79a and 7% are shown, the ends 0tv which may be attached to the cross slide. Thus, involute surfaces on the teeth on the broach may be checked by transverse movement of the cross slide 74. The transverse movement of the cross slide 74 is accomplished by manually operated mechanism including the hand wheel 80.

In order that the checking of the involute surfaces and lead of the teeth of the broach may be used to produce permanent records, a twin chart recording unit indicated generally at 82 is provided. Lead and involute charts may be produced automatically by this unit as indicated at 84 and 86 respectively. At the same time, if desired, the actual measuring instrumentalities may be suitably connected, as by electrical circuits, to indicating dials indicated generally at $8.

As mentioned at the outset the present apparatus is designed particularly for use with relatively massive broaches and accordingly, the apparatus is provided with a platform 90 having guard rail structure d2 thereabouts, access to the platform 9% being provided by an inclined ladder indicated generally at 94.

The present apparatus was designed primarily to facilitate and simplify accurate checks of both lead'and involute on relatively massive broaches. In order to accomplish this, special apparatus was designed adapted to receive the broach in slightly inclined relationship so as to permit its temporary location in the simplest'possible manner.

In order to permit the broach B to be hoisted into position and safely supported while it is coupled to the lead bar 22, an approximate locating support 96 is provided which is vertically adjustable in the T-slots 16 to accommodate different size breaches. The locating support 96 is provided with a suitably shaped notch or recess to engage the upper end of the broach in approximately its final position but located slightly rearwardly from such position so that when the broach is coupled to the'member 20, it is moved out of contact with the supporting surfaces of the locating support as. As a result of the provision of this arrangement it is possible to move the broach into approximate position by suitable meanssuch for example as a crane, and to position its lower end on the center 30, after which the broach may be inclined to bring its upper end into engagement with the locating support 96. Thereafter, the center 3% may be elevated to bring the upper end of the broach into coupling relationship with the socket portion 24, or the socket portion 24 may be vertically movable so as to be coupled to the broach without vertical movement of the center 31 At the same time, the measuring instrumentalities are correspondingly inclined in their planes of movement.

The apparatus is quickly adjustable for broaches of different lengths by suitable vertical adjustment of the bearings 14 and 18 and of'course the lead bar 22 and lead nut 28 may be removed and replaced with one of appropriate lead to correspond to the particular broach being checked.

The drawing and the foregoing specification constitute a description of the improved broach'checker in such full, clear, concise and-exact terms as to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claims.

What I claim as my invention is:

1. Broach checking apparatus comprising a base having a vertically extending column at its rear, said column having a slightly upwardly and rearwardly inclined front "face, an upper bearing at the top face of said column, an

intermediate bearing on the front face of said column, a lead bar extending generally vertically in parallelism with said front face on said bearings, a center on said base in alignment with saidbearings, coupling means on the'lower end of said lead bar for engaging the upper end of a broach including releasable drive means to rotate the same as a result of rotation of said lead bar, a slide movable up and down on the front face of said column, a nut on said slide between said bearings and engaging said lead bar, an indicator on said slide having a movable finger engageable with a longitudinally extending element of the broach to compare its angularity with lead elements on said lead bar, and means for raising and lowering said slide in lead checking strokes.

2. Broach checking apparatus comprising a base having a vertically extending column at its rear, said column having a slightly upwardly and rearwardly inclined front face, an upper bearing at the top face of said column, an intermediate bearing on the front face of said column, a lead bar extending generally vertically in parallelism with said front face on said bearings, a center on said base in alignment with said bearings, coupling means on the lower end of said lead bar for engaging the upper end of a broach including releasable drive means to rotate the same as a result ofrotation of said lead bar, a slide movable up and down on the frontface of said column, an approximatinglocating support on said column below said intermediate bearing for receiving the upper portion of the broach in approximate alignment with said coupling means, a nut on said slide between said bearings and engaging said lead bar, an indicator on said slide having a movable finger engageable with a longitudinally extending element of the broach to compare its angularity with lead elements on said lead bar, and means for raising and lowering said slide in lead checking strokes.

-3. Apparatus as defined in claim 2 comprising an approximate angular locator on said slide having a movable finger engageable with a longitudinally extending element of the broach to locate itangularly in position to cooperate with said indicator.

4. Apparatus as defined in claim 2 comprising means for raising and lowering said center to elevate the upper end of the broach into engagement with said coupling means.

5. Apparatus as defined in claim 2 comprising involute checking mech'a nism comprising a cross slide on said base, drivemeans connecting said center to the broach, a base roll secured to said center, means for effecting rotation ofsaid base roll proportional to traverse of said cross slide, a second indicator on said cross slide, and a inovabie finger on said secondindicator movableon a broach tooth to check its involuteform.

'6. Apparatus as defined in claim 5 in which said coupling "means comprises a socket adapted to receive the upper end ofa broach to be checked, and said releasable drive means serves to couple said socket to the broach to drive the broach in rotation upon rotation of said lead ban -onto release the broach for rotation by said involute checking mechanism.

7. Broach'checking apparatus comprising a base having a vertically extending column at its rear, said column havingan upper bearing atth'e top of its front face and an intermediate bearing on the front face intermediate its upper and lower ends, a lead bar extending generally vertically'in parallelism with the front'face of said column and mounted for rotation by said bearings, a center on the base in alignment with said bearings, coupling means -'on the'lower end of said lead bar for engaging the upper end of a broach including releasable drive means to'rotate the broach upon rotation of said coupling means, a slide movable up and down on the front face of the column, a

nut on the slide between said bearings and engaging said lead bar, an indicator on said slide having a movable finger engageable-with a longitudinally extending element of the broach to compare its angularity with lead elements on said lead bar, and means for raising and lowering said element in lead checking strokes.

8. Broach checking apparatus as defined in claim 7 com- .pri sing a locating supportbelow said coupling means en gageable with the upper end of a broach the-lower end of which is positioned on'said center to support said hroach in position for engagement by saidcoupling means.

9, Broach checking apparatus as defined in claim 7 comprising involute checking mechanism including a cross slide on said base, selectively engageable drive means connecting said center to the breach, a base roll secured to said center, means for effecting rotation of said base roll proportional to traverse of said cross slide, a second indicator on said cross slide and a movable finger on said second indicator engageable with a broach tooth to check its involute form.

References Cited in the file of this patent UNITED STATES PATENTS 1,904,130 Garms et al Apr. 18, 1933 1,956,812 Smith May 1, 1934 2,108,414 Schurr Feb. 15, 1938 2,563,000 Bean Aug. 7, 1951 

